1. Field of the Invention
This invention relates to a housing mounted on a vehicle which provides easy and effective access for servicing and maintaining hydraulic control components housed therein by virtue of its pivotal mounting to the vehicle. More particularly, it is concerned with a vehicle having a control housing mounted thereon whereby the housing is provided with structure enabling it to pivot between a substantially upright position for normal operation and a horizontal position for servicing and maintenance. The invention also discloses the use of a control limiter for preventing simultaneous opening of a plurality of valves to a single hydraulic tool circuit to prevent overloading of the tool circuit from excessive hydraulic input.
2. Description of the Prior Art
The advantages of using hydraulic power to operate a variety of hand held and vehicle mounted equipment are increasingly becoming recognized by individuals and companies who must operate service vehicles in remote locations. Hydraulic powering circuits avoid difficult and complicated mechanical transmissions which are difficult to relocate or extend for remote operations. Electrical power avoids some of these difficulties, but involves inherent losses in converting mechanical power to electric power, as well as being limited in the amount of power an electrical conduit can effectively and efficiently transmit. Thus, hydraulic power circuits represent, in certain environments, advantages over either mechanical or electrical power transmission.
In some operations, it may be desirable to provide pneumatic, electrical and hydraulic power outlets for use at a remote site. In such applications, the hydraulic unit may be used to power not only hydraulic tools but also either an air compressor for pneumatic tools or an alternator for electrical power supply. In such circumstances, the hydraulic power circuit may involve a series of controls, dials and valves in order to enable selective operation of each of the circuits.
However, in such multi-function units, it has often been difficult to efficiently locate and effectively connect the various tool-powering circuits. In particular, when the housing carrying the control mechanisms and valving is mounted on the vehicle, it must often be in close proximity to the other power supply components, making maintenance extremely difficult. Routine maintenance operations have ordinarily been difficult to effect or required removal of the entire control unit housing, operations which made repairs more time consuming and expensive.
In addition, the control housing has advantageously been equipped to provide hydraulic power to the air compressor, alternator or to a single tool-powering circuit. However, users of the vehicle may attempt to employ two tool circuits simultaneously, when in fact only one circuit is available. When a tandem output hydraulic pump is used and valves from both pump outputs are opened to a single tool circuit, the resultant overloading of the system results in intermittent operation of the hydraulically powered tool circuits and eventually system overload and failure. Thus, the maintenance problem has been increased by the failure to provide a suitable limiting device which permits alternate opening of valves leading to a single tool output circuit.